Johnson 15HP 1997 engine re-assembly question...

[bigfish55]

I tore this motor apart about 6 weeks ago (my first go) and after much research and getting parts, I got it back together fine and had the whole thing mostly ready to test. While waiting for my last couple of parts, I stumbled across some writings by a guy named LeeRoy Wisner, who seems like he knows a lot about these motors. A point of great importance was something he called "internal concentricity" as it pertains to the alignment of the con rods and caps. I had checked the alignment on the outside of the castings, but not the inside surfaces that house the bearings.

Since I had the time, and didn't want to chance it, I pulled the power head again and decided to check it right. Everything was OK there, but my concern is that the sealant I used on the crankcase halves (Permatex 51817 anaerobic gasket maker gel) had not set up at all after a week. I've since read of other options, but I'm wondering if anyone else here has ever used that stuff? The mating surfaces were absolutely flat, smooth, and burr free, so I know it wasn't that. What sealant should I be using for this motor?

 

[flyingscott]

If you are talking about what squeezed out of the crank halves no worry. loc-tite 518 sets up in the absence of oxygen so the only thing that sets up is whats left between the crank halves. There is a primer to help speed that up. Loc -tite 518 is the correct sealer to use.

 

[thatone123]

I rebuilt one of these last year and had similar problems. My engine was too tight after wrestling with all the proper exact alingments you speak of and thinking I had them wrong. I gave up on the motor but went back to it after a month or 2 and found it seemed to have gotten more loose over time. It started after a while and ran good. I got some good advice here about it. Ol' Leeroy has a great site about these motors and as far as I know it is the most complete website about ANY outboard and says something about how much the OMC 9.9/15 is valued by many. I have seen these engines so misused, abused and everything one can imagine you should not do with an engine and they still come back smiling and running. Either a Genius designed these or it was a complete accident.

 

[bigfish55]

Actually the non set up sealant was not what had squeezed out during assembly. I had already wiped that clean. It was on the mating surfaces of the crankcase halves.

Now I have another problem. When first reassembled the motor, everything went together fine. The crankshaft was nice and tight with the new rings and rotated fairly smoothly. After taking it apart again and checking the rod alignments, when I put it back together the crankshaft goes for maybe a half turn and then "hits" something and will not turn any more. I know the crankshaft is installed right. Both halves fit together with no gaps anywhere. I've tried it with and without the bolts (not torqued...just snug) and with the pin in and out. It is also well oiled pretty much everywhere. Something is keeping the crank from rotating.

I tried using an .005 feeler gauge at the point where it stops, but it fit through every spot I could get it into. It almost feels like the rod cap is hitting the bottom of the cylinder as it turns, but I haven't found that to be the case via the feeler gauge. Any ideas? I hate would hate to have to sent this to the machine shop and have them do it, especially since I did it the first time myself with no problems at all.

The only other possible useful information I can give is that only removed the lower crankcase and the intake manifold. I left all of the other bolt on gasketed parts on the powerhead.

 

[flyingscott]

Make sure the locating pins are in good condition and in the right position. Loc-tote 518 remains pliable.

 

[bigfish55]

I only have 1 locating pin on this motor and it doesn't matter if it's in or out...same thing. I didn't use Loc-tite 518. I used Permatex 51817, but I'm going to use the Loc-tite if I can ever get this other problem fixed. When the crank stops, it's a definite "clunk", like there is a bolt or something in the cylinder (there isn't),and it isn't going any further. Not just like metal rubbing against metal if that helps at all.

 

[thatone123]

I think mine went clunk too. Hard to remember now. I remember it was frustrating to have to tear apart the bearings a number of times. Finally got it back going again per post above. Wish I could be more help. I lost all track of marking the bearings and etc. and think I got lucky.